With the spread of smartphones and the explosive increase in the amount of information processing due to big data, the power consumption of information equipment has become a problem, and there is a demand for next-generation memory devices with low power consumption, high recording density, and non-volatile properties. It is increasing.From this point of view, multiferroic materials having both magnetism and ferroelectricity are attracting attention.If the correlation between magnetism and ferroelectricity is strong enough and the magnetization direction can be reversed by an electric field, a simple element structure with low power consumption, high recording density, and high stability can be achieved while taking advantage of the current characteristics of magnetic memory such as non-volatility and high stability. It is said that the next-generation magnetic memory that it has can be realized.

　This time, the research group succeeded in stabilizing bismuth ironic acid cobaltate, in which iron is partially replaced with cobalt, in the form of a thin film capable of evaluating ferroelectricity.As a result of the dielectric property evaluation, it was confirmed that the thin film material was a ferroelectric substance at room temperature.Furthermore, by devising the growth direction of the thin film, it was clarified that the properties of the magnet change according to the temperature, and the properties of the magnet that disappeared at low temperature appear at room temperature.It also has the property of storing electricity.

　This result is an experimental proof of the coexistence of ferromagnetism and ferroelectricity at room temperature, which is the key to the realization of a new magnetic memory, for a bismuth thin film of iron iron cobalt acid.Since the correlation between ferromagnetism and ferroelectricity has been confirmed, it is expected to lead to the development of next-generation magnetic memory with low power consumption, high-speed access, and large capacity based on a new principle.